Explosive



i5 Dynamites which Patented Dec. 19, 1933 EXPLOSIVE Norman G. Johnson,

to E. I.

Woodbury, du Pont de Nemours &

N. J., asslgnor Company, Wilmington, Del., a corporation oi Delaware NoDrawing. Application July 8, 1931 Serial No. 549,578

10 Claims.

My invention relates particularly to improved nongelatinous dynamitecompositions and more especially to dynamite compositions of apulverulent or granular nature which will flow or 5 pour freely.

Explosives of the dynamite type are commonly termed high explosives indistinction from explosives such as black powder, which are designatedas low explosives, the difference in 10 terminology between high and lowexplosives coming from the differing velocities of combustion. Whereas,explosives such as black powder burn at velocities in the neighborhoodof 300 m/sec. for columns of explosives approximately 1%" in diameter,high explosives such as dynamites are consumed so rapidly that thedecomposition is termed detonation, the velocity of detonation in thecase of dynamites ranging from 1200 to 6000 m/sec. for 1%" cartridges.The high velocity of dynamites is due commonly to the presence ofnitroglycerin in the formula.

Black blasting powder has ordinarily been used in the past in granularform, in which form the powder could be loaded into the borehole simplyby pouring. Dynamites, on the other hand, have-customarily been put upin much different form. The usual method of packaging dynamites has beento punch the material tightly into the paper shells of the cartridges.These shells have then been folded over or crimped at the two ends. Whenthus packed, the dynamite has usualLv been shot directly in the wrapper,the paper container being considered an ingredient of the dynamite. Withsuch a method of use of dynamites the possession of good pouring or freeflowing properties was obviously of no advantage.

Occasions frequently arise, however, where it is very desirable to beable to pour the dynamite into the bore-hole, as is the case whengranular black powder is used. In order to do this it is necessary thatthe dynamite be removed from the cartridge, either by direct removal ofthe entire shell or by the unfolding of one end of the cartridge, sothat the dynamite may be poured out. The more convenient method 01'using high explosives which are to be loaded in such a manner is to usean explosive which has been packed in bags in the first place, rathersothan in cartridges. Because of the physical properties of the usualdynamite compositions,

these explosives are not adapted to such a method of use and have theproperty of flowing freely to a very slight extent, if at all.

can' be loaded by pouring in the bore-hole are frequently desired inquarrying work. It is often advantageous to use small diameter holes,not more than 2 inches in diameter for example, because of the saving indrill- 0 ing costs. In such cases it is the practice often (Cl. 521l) tochamber the holes, that is to-say, to set off successive shots in thebottom of the hole until this part has been enlarged to a considerablyincreased volume. In blasting such chambered holes, the use offree-running explosives is particularly advantageous, since suchexplosives will fill the enlarged portion of the hole almost completely.

The high explosives used in such work prior to the present inventionhave ordinarily contained a large amount of sodium nitrate in theircompositions, together with ammonium nitrate usually, and carbonaceouscombustible materials, while small percentages of nitroglycerin havecustomarily been used as sensitizing agent and explosive ingredient.Sodium nitrate has frequently been used in such explosives in amounts upto -60 per cent by weight of the entire explosive composition. Whereasthe explosives of such nature heretofore in use have given satisfactoryresults in generaltheir properties have not been all that could bedesired with respect to their ability to pour freely into the bore-hole.

The object of my invention is to produce a new and. improved explosivecomposition for such use, which possesses all the advantages inexplosive properties of the dynamite previously used and which has inaddition the property of flowing freely to an unusual degree. Furtherobjects will be apparent as the description of my invention proceeds.

I have discovered that this desirable result is obtained by the use ofan improved form of sodium nitrate or other metallic nitrate in place 01the common form previously used. Whereas the nitrate in general use insuch explosives has consisted of very finely ground material of eithernatural or synthetic origin, or of material of varying forms and crystalsize, I find it desirable to use a metallic nitrate in the form of smallspherical pellets. While the nitrate used will preferably be sodiumnitrate, because of its advantages from the economic point of view, andfrom the point of view of oxidizing properties, I do not intend to belimited in my invention to this material. Potassium nitrate, calciumnitrate and other metallic nitrates in the form of pellets are intendedto be included within the scope of my invention. Also, a mixture ofthese nitrates may be used for this purpose.

The pelleted material described above will be strikingly diiferent fromthe ordinary sodium nitrate as used in explosives. The materialpreviously available has ordinarily been ground to a definite degree offineness but the particles are present in a variety of different shapesand forms. Improved pelleted material, on the other hand, exists in theform of smallballs of such size that they should ordinarily pass an8-mesh sieve and be held on 30-mesh. The process by which said pelletsmay be obtained may vary within wide limits. One process consists ofhaving a molten material sprayed through small openings into a coolinggaseous mixture where the material will immediately harden to smallspherical pellets, usually somewhat hollow in nature. Various othermethods of forming the pellets are available also.

1am aware that ammonium nitrate in the form of coarse grains and ofhollow spherical granules has been used in explosive compositions. Suchforms of this material for use in dynamites are described in U. S.Patent 1,113,- 275 (Woodbury) and in U. S. Patent 1,613,335 (Symmes).However, the use of pelleted ammonium nitrate is not suitable toaccomplish the objects of the present invention. Ammonium nitrate in theform of hollow granules was used by the foregoing investigators for thepurpose of obtaining a low density dynamite. Explosives containing suchgranules of ammonium nitrate could not be, or remain, free-runningbecause of the great hygroscopicity of the compound, which would tend tocause it to cake.

By the use of sodium nitrate or other solid metallic nitrate, in thedesired pelleted form in dynamite compositions, I obtain a highexplosive of extraordinary properties, which is perfectly adapted to thedesired use where a free-running explosive is wanted. An explosivecontaining such pellets may be poured into a borehole in such manner asto fill completely all the crevices of the bore-hole, without need oftamping.

While various compositions of ingredients may be used according to myinvention in the manufacture of free-running explosives, the followingwill illustrate one satisfactory composition:

While I have described specifically the use of sodium nitrate inpelleted form in the above illustration, it should be understood thatany solid metallic nitrate in pelleted form may be used in place of it.I may prefer also to use only a portion of the sodium nitrate or othermetallic nitrate present in the explosive in the form of pelletedmaterial, a suflicient percentage of pelleted nitrate being present togive the desired free-running properties to the explosive.

From the foregoing description of my invention it will be apparent thatI do not intend to be limited except as indicated in the followingpatent claims:

I claim:

1. A non-gelatinous dynamite composition. containing as an ingredient asolid metallic nitrate in the form of spherical pellets.

2. A non-gelatinous dynamite composition, containing as an ingredient analkali metal nitrate in the form of spherical pellets.

3. A non-gelatinous dynamite composition, containing as an ingredientsodium nitrate in the form of spherical pellets.

'4. A free-flowing non-gelatinous dynamite composition, containing as aningredient a solid metallic nitrate in the form of spherical pellets.

5. A free-flowing non-gelatinous dynamite composition, containing as aningredient an alkali metal nitrate in the form of spherical pellets.

6. A free-flowing non-gelatinous composition, containing as aningredient sodium nitrate in the form of spherical pellets.

7. A free-flowing non-gelatinous composition, containing as aningredient potassium nitrate in the form of spherical pellets.

8. A free-flowing non-gelatinous composition,

containing as an ingredient calcium nitrate in the form of sphericalpellets.

9. A free-flowing non-gelatinous composition, containing as aningredient sodium nitrate in the form of spherical pellets, of such sizethat they will pass a sieve having 8 meshes to the inch and will be heldon a sieve having 30 meshes to the inch.

10. A free-flowing non-gelatinous dynamite, comprising 3 to 20 per centnitroglycerin, 20 to '70 per cent spherical pelleted sodium nitrate, 5to 20 per cent carbonaceous combustible material, and an antacid.

NORMAN G. JOHNSON.

